Abstract: Abstract: Objective To evaluate the serum vitamin D (Vit D) deficiency in hospitalized patients with community- acquired pneumonia (CAP), and to investigate its association with clinical outcomes and disease severity. Methods A total of 96 CAP patients admitted to our hospital from June 2016 to February 2018 were selected in this prospective study. The general characteristics, clinical data and biochemical indexes in 48 hours of admission were measured in 96 CAP patients. The patients were divided into three groups by serum levels of 25-hydroxyvitamin D ［25(OH)D]: <10 µg/L group (n=46), 10~ 20 µg / L group (n=30) and ≥20 µg / L group (n=20). All these indexes were compared between three groups. Logistic regression analysis was used to investigate the relationship between 25(OH)D and the severity of CAP. Results In total 96 CAP patients there were 76 patients (79.2%) with Vit D deficiency, [25(OH)D<20 µg/L]. Prevalence of severe deficiency of Vit D ［25(OH)D<10 µg/L］ was far more (63.6%) in high-risk CAP patients (CURB-65 score 3-5) than that of low-risk CAP patients (39.7%, CURB-65 score 0-2). And when serum 25（OH）D <10 µg/L, the risk of developing high-risk CAP was 4.247 times of those with 25（OH）D≥20 µg/L (95%CI:1.041-17.337， P=0.044). Conclusion Hospitalized CAP patients have low Vit D status, and which is associated with the severity of CAP. The risk of aggravation is significantly higher in CAP patients with severe Vit D deficiency.

Key words: vitamin D, pneumonia, Logistic models